Physiological changes in caged layers during a forced molt. 4. Leucocytes and packed cell volume

Area of Science:

• Avian physiology
• Poultry science
• Animal science

Background:

• Force molting is a common practice in commercial poultry production to rejuvenate laying hens.
• Understanding the physiological responses to force molting is crucial for optimizing hen health and productivity.

Purpose of the Study:

• To investigate the hematological changes, specifically packed cell volume and circulating leucocyte numbers, in force-molted Single Comb White Leghorn (SCWL) hens.
• To differentiate the effects of feed withdrawal and water deprivation during the force molting process.

Main Methods:

• Two trials involving commercial SCWL hens subjected to force molting (FM) at 70-72 weeks of age.
• FM protocol included reduced photoperiod, 12-day feed removal, and 1-day water withdrawal (Trial 1).
• Control (CON) groups received ad libitum feed and water with standard photoperiod.

Main Results:

• Force-molted hens showed a significant increase in packed cell volume (PCV) and eosinophilia during the nonlaying period.
• Total leucocyte and monocyte numbers increased significantly at specific time points post-molt.
• Changes in lymphocyte, heterophil, and basophil counts were inconsistent across trials.

Conclusions:

• Increased PCV, eosinophilia, and elevated leucocyte/monocyte counts are associated with force molting in caged SCWL hens.
• These hematological shifts suggest physiological stress and adaptation during induced molting.
• The findings provide insights into the body's response to feed deprivation and altered environmental conditions during force molting.